Numerical simulation of residual stress in multipass weld joint of ultrafine-grained Q460 steel

Based on thermal elastic-plastic theory, a three-dimension finite element model of multipass weld joint of ultrafine-grained steel was built to simulate the residual stress field using Ansys software,and the according characteristics of residual stress distribution were also analyzed. Results show that peak value of longitudinal residual stress on the surface of each weld bead decreases gradually during the welding process. After welding,relatively higher longitudinal residual stress with peak value near the yield stress was found in the weld bead and its adjacent zone. Transverse residual stress at the location of weld root is obviously higher than the other locations but its peak value is lower than the yield strength. Von-Mises equivalent stress is larger in the area of arc-starting and arc-extinguishing where the stress reaches yield strength,but Von-Mises stress at the other locations is lower than the yield strength.